The current industry practice for extracting bitumen from oil sands and the like is the hot water process. This process typically involves pre-crushing as-mined oil sands and conditioning the oil sands by mixing it with large amount of hydrocarbon diluent. Next step is based on heating oil sands with hot water and steam to yield a slurry. During this step bitumen flecks became less viscous. Bitumen flecks separate mainly from the surface and partially from pores of the sand grains. This process is done in a rotating kiln with continuous agitation of the raw material. Inside the kiln there are blade that while rotating agitate the sand and move it to the lower part of the kiln. The liquid bitumen slurry concentrate at the bottom of the inclined kiln. The saturated steam and raw material are both supplied to the inlet port of the kiln. The bitumen slurry is discharged from the bottom outlet port of the kiln. The typical sized of the working zone of the inclined rotating kilns are 2.5 m in diameter and up to 20 m in length. To better separate the bitumen product two or more stages of the hot water and steam treatment can be used.
The heat losses of such plants can reach up to 30% as components are supplied and discharged at partially open ports as well as significant heat losses are due to design of the working zone of the kilns.
The main reasons that prevent the usage of such technology are:
1) power requirements by this technology is 5.5-8 times higher than the ones at extracting conventional oil;
2) significant soil and ground water contamination resulting from disposal of tailing streams containing some residual amount of bitumen to large tailing ponds;
3) high emissions of combustion products such as CO2, NOx, CO, etc. at production of the technical saturated steam.